Facial and trigeminal nerve reflexes

Question 1

2 tests to evaluate the trigemial nerve

Answer 1

1. blink reflex
2. trigemino-trigeminal reflex testing

Question 2

2 tests to evaluate facial nerve

Answer 2

1. blink reflex
2. Direct facial nerve stimulation

Question 3

3 clinical usefulness of these tests

Answer 3

1. Px for recovery with idiopathic facial paralysis
2. Differentiating between central vs peripheral nerve dysfunction
3. assessing presence and extent of brainstem Lx in dogs with multifocal CN deficits

Question 4

What is the blink reflex :)

Answer 4

stimulation of the trigeminal or facial branches –> reflex contraction of the ipsilateral orbicularis oculi muscle

Question 5

blink reflex

What nerve branches can be stimulated in the blink reflex

Answer 5

Trigemial:
- infraorbital
- supraorbital (frontal)
- ZygomatIic

Facial
- Internal auricular

slide 9

Question 6

blink reflex

What type of waveform is recorded

Answer 6

Reflex Evoked Muscle Potential (REMP)

(obtained by stimulating the facial or trigeminal branches and record in the orbicularis oculi muscles)

slide 16

Question 7

Blink reflex

Describe R1

Answer 7

R1:
Trigeminal nerve branch –>
pontine sensory nucleus of V –>
Motor nucleus of VII
Facial nerve branch -> ipsi orbicularis oculi muscles

slide 11

Question 8

Blink reflex

Describe R2

Answer 8

R2:
Trigeminal nerve branch –>
Spinal tract of V –> nucelus of spinal tract of V –>
to bilateral motor nuclei of VII –> bilateral orbicularis oculi muscles

Essential to distinguish afferent (V) vs efferent (VII) arc involvement (analogy to D+ and C+ PLRs)

slide 12

Question 9

Describe R3

Answer 9

When specifically stimulating small-diameter, high-threshold afferent unmyelinated fibers

Trigeminal nerve branch (small) -> spinal tract of V -> nucleus of spinal tract of V -> ipsi motor nucleus of VII

slide 13

Question 10

Blink reflex

understand interpretation based on lesions slide 19-23

Question 11

Direct facial nerve stimulation